The present invention generally relates to a thermal recording apparatus, such as a heat-sensitive recording apparatus and a thermal transfer recording apparatus, more particularly, to a thermal recording apparatus suitable for recording data on a large recording sheet.
Conventionally, in an automatic CAD (Computer Aided Design) machine or the like which draws a diagram on a large recording sheet of size A0 or A1, for example, a thermal recording apparatus, which employs an in-line type thermal head having an array structure, is used because of high-speed drawing, lower noise and easier maintenance, as well as a so-called pen plotter. However, the practical use of elongated thermal heads
designed to cope with sizes A0 and A1 is not easy because they have a low production yield, thus increasing the manufacturing cost, and a low maintainability. In this respect, a plurality of commercially available heads for size A3 are connected in the line direction to ensure data recording on a large area, such as size A0 or A1. In this case, it is necessary to secure the continuity of a recording image at the jointed portion between the thermal heads.
In a conventional thermal recording apparatus, as shown in FIG. 1, there are a plurality of platen rollers 61 and 62 (the two in the illustrated example) located adjacent to each other with their axial directions being in parallel to each other, and thermal heads 63 and 64 are respectively provided at the platen rollers. Thermal heads 63 and 64 are located in parallel to respective platen rollers 61 and 62 in such a way that they can make contact with the platen rollers at their resistance heating elements 65 and 66 and can move away therefrom. In addition, thermal heads 63 and 64 are located at opposite sides in the axial directions of platen rollers 61 and 62 so that effective recording regions A and B determined by heating elements 65 and 66 become continuous in the line direction, i.e., in the longitudinal directions of the thermal heads. Heating elements 65 and 66 are selectively driven while moving continuous recording sheet 67 in the arrowhead direction in FIG.1, so that thermal head 63 records an image on region A side and thermal head 64 records an image on region B side.
However, the above-described conventional thermal recording apparatus requires that a plurality of platen rollers be provided in association with the individual thermal heads, which inevitably enlarges the apparatus and increases the manufacturing cost.